Lisa Holland

Foreign Affairs Correspondent

Turkey's Prime Minister has blamed the bomb attack on the American Embassy on a far-left domestic militant organisation called the Revolutionary People's Liberation Party-Front, or DHKP-C.

But normally they target the Turkish establishment not foreign interests, although the far-left group may be trying to punish the Turkish government for its close ties to the US.

Islamist radicals, far-left groups, far-right groups and Kurdish separatist militants have all carried out attacks in Turkey in the past.

The immediate finger of suspicion would have pointed towards either al Qaeda or the PKK (Kurdish Workers' Party) which is waging a guerrilla campaign against the Turkish government.

The suicide bomber who killed himself in the attack is thought to have been Turkish.

The suicide bomber was going through an X-ray machine

Turkey has now promised greater protection for foreign diplomats.

The attack follows the killing of the US Ambassador Chris Stevens and three others in Benghazi in eastern Libya last September.

America blamed al Qaeda linked militants for that attack but the State Department had to defend itself against accusations it hadn’t listened to demands for better security.

Britain knows only too well how easy al Qaeda finds it to strike in Turkey. Bomb attacks on the British consulate and the HSBC bank headquarters in Istanbul left at least 27 dead and up to 400 injured in November 2003.

The UK's top diplomat in Istanbul, Consul-General Roger Short, was amongst at least 14 people killed in the attack on the consulate.

The Turkish authorities said the attacks were carried out by suicide bombers, reportedly linked to al Qaeda. Istanbul was thrown into chaos by the twin blasts.

The US embassy is in the Turkish capital of Ankara

The explosions followed suicide bomb attacks two synagogues in Istanbul that killed 25 people.

But Turkey also has a home-grown security problem - the PKK. The banned organisation has been fighting a guerrilla war for decades.

Violence has escalated of late. In September of last year, a suicide bomber struck a police station in Istanbul, killing one officer and injuring seven people. The attacker reportedly blew himself up at the station's entrance, causing part of the building to collapse.

The Turkish government stepped up operations against the separatist Kurdish rebels, conducting air strikes in northern Iraq where the group operates. An attack by the PKK on a foreign target seems unlikely. Although the US, the EU and Turkey have deemed the PKK a terrorist group, it has focused its campaign largely on domestic targets.

There have been reports that jailed PKK leader Abdullah Ocalan is expected to issue a call within 10 days for the group to declare a ceasefire.

On January 9, the Turkish government and the Kurdish group reportedly agreed on a peace roadmap to end nearly three decades of hostility.

Under the reported roadmap, Ankara would grant wider rights to the PKK. The group also demands that Turkey recognise Kurdish identity in its new constitution and release hundreds of activists jailed for links to the PKK. The group has been fighting for an autonomous Kurdish region inside Turkey since the 1980s.

Turkey has felt the full brunt of the civil war in Syria and a second pair of Patriot missile batteries being sent by Nato countries to defend Turkey against possible attack from Syria recently became operational.

Turkey has led calls for international intervention in Syria and is hosting hundreds of Nato soldiers from the US, Germany and the Netherlands who are operating a Patriot system along its border with Syria.